Year: 2023
Type: dissertation
Abstract: Climate change and land use are recognised as primary drivers of global biodiversity decline, and pose a significant threat to freshwater ecosystems. The ecological, economic, and aesthetic importance of freshwaters necessitate urgent action to enhance their resilience to accelerating environmental change. Riparian broadleaf woodlands have been increasingly promoted for this purpose, but evidence demonstrating their effectiveness is scarce. \nUsing a 40-year macroinvertebrate dataset from 16 headwater streams in upland Wales, UK, this thesis aims to address the hypothesis that broadleaf woodlands enhance stream ecosystem resilience to climate change. Specifically, long-term community trends and multiple facets of ecological stability were assessed relative to water temperatures and discharge, water chemistry (acid versus circumneutral) and contrasting catchment character typical of upland management (sheep-grazed moorland, conifer plantations, and semi-natural broadleaf woodlands). \nSince the start of monitoring (1981), progressive structural and functional changes have occurred in these streams, with indications that detritivores were among the taxa underlying these trends. While enhanced resilience of population- and community-level properties in broadleaf streams was evident, it was also apparent that changes were far-reaching. Extreme conditions including high temperatures and complex effects of dry weather were commonly associated with community change, but a large amount of unexplained variation remained. Particularly deleterious effects of conifer forestry were highlighted, in addition to vulnerabilities of rare taxa. \nDespite the underlying complexities of stream communities and their dynamics, stream type remained the best predictor of taxonomic and functional diversity. Thus, coupled with their widely acknowledged benefits for biodiversity and stressor regulation, riparian broadleaves remain favoured candidates for climate adaptation. However, interventions may be required at broader scales than just riparian zones. \nOverall, this research provides sought-after evidence of climate and catchment character effects that enhances our understanding of ecological resilience, with important implications for river management in the face of global environmental change.
Author: Joyce, Fiona
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDGs: Life on land, Climate action
Open Access status: green
OpenAlex ID: W7046867981